If you're in any doubt, then write an API.

bands_without_mbids.php

<?php

function is_instance_of( $item ) {
	return "CLAIM[31:{$item}]";
}

function is_instance_of_band() {
	return is_instance_of( '215380' );
}

function has_musicbrainz_artist_id() {
	return "CLAIM[434]";
}

function notº( $claim ) {
	return "NO{$claim}";
}

function andº( /* .... */ ) {
	$args = func_get_args();

	return join( ' AND ', $args );
}

function execute( $query ) {
	// That's close enough.
	echo sprintf( "http://wdq.wmflabs.org/api?q={%s}\n", urlencode( $query ) );
}

execute( andº( is_instance_of_band(), notº( has_musicbrainz_artist_id() ) ) );
// => http://wdq.wmflabs.org/api?q=CLAIM%5B31%3A215380%5D+AND+NOCLAIM%5B434%5D